The present invention relates to inflators for vehicle airbags and, more particularly, to an inflator incorporating a multi-layered filter and an outer body wrap that substantially encloses the filter and is conformable to the thickness of the filter material.
Conventional inflators may include an inner tube defining a combustion chamber, a metallic mesh filter enclosing the inner tube for filtering combustion products, and an outer housing or tube enclosing the filter and the inner tube. The outer tube is generally a rigid cylindrical vessel which may be extruded, roll-formed and welded, or otherwise metal-formed from carbon steel, stainless steel, or aluminum. Generally, the outer tube is sized to conform to a predetermined envelope size for the inflator, or to accommodate a desired thickness of filter material between the inner body portion and the outer tube.
However, the outer tubes used in conventional designs tend to be rigid, relatively heavy and expensive. In addition, due to their rigidity, conventional outer tube designs are not necessarily adaptable to changes in the design of the other inflator components (for example, changes to the diameter of the inner tube, or changes to the type or thickness of filter material used.) Conventional rigid outer tube designs are also bulkier than is needed for functioning of the inflator, due to the need to provide internal clearance to allow for insertion of the filter material during inflator assembly.